WHEN there are issues concerning the wireless network in terms of ground base stations (BSs) malfunctioning or a massive increase in network traffic in a wireless network, a promising solution is to use unmanned-aerial-vehicles (UAVs) as temporary BSs [1]}, [2]}, [3]}. The mobility and high-altitudes of UAV-BSs allow flexible deployment deployment and provide rich line-of-sight (LoS) links [4]}. To efficiently deploy UAV-BSs, researchers have focused on designing the deployment strategies [5]}, [6]}, trajectory optimization [7]}, [8]}, [9]} and power control [10]}, [11]}, [12]}.
